[iMore]

Hello, All!

I’m new here… recently purchased a 2011 335i/N55! However, I've been having a hell of a time tracing down a small boost leak.

Code 28A0 has been off and on for weeks now.

Only happens during WOT at higher boost. (Above about 65mph) l’ll get the Half Engine error, but the car sounds and feels perfectly normal. Outside of that, no other issues and car drives perfectly. Car is completely stock.

BUT, just last weekend, while ironically picking up a smoke machine to test, the service engine light lit up! Now the car is showing the P112f code.

So I now have both 28A0 and P112f.

I've upgraded the charge pipe, replaced the vacuum tube running over the VC (Part 11657588771) and capped off the exhaust flap line. Each of which were believed to be the issue, at the time. However, even after all that I'm still here in the same spot... and getting worse.

I was able to smoke test - but it seems like it's coming from the underside of the engine, so I was not able to pinpoint it without lifting the car and getting underneath. I finally got it up on some ramps and was able to crawl under. I removed the inlet pipe as initially it looked like it was coming from that, but that wasn't the case. Seems to be creeping up from the underside, just to the right of the lower end of the inlet tube. Getting under the car, I can’t seem to see where the smoke is creeping from either! Extremely frustrating!!

I'm giving up for now. Thinking I may just order the turbo outlet pipe and try that… But, until then, any ideas/thoughts??

Vehicle has 140k miles. Well maintained by previous owner and in great shape in and out. For context, I had the valve cover replaced shortly after picking it up, and it didn’t seem to have this issue prior.

Thank you all in advance!

[BashShah]

you know, I had a similar issue, and you can not tell with these braided lines what is melted under it....or deteriorated.
but it seems to be the line that goes to the turbo itself.
why not just replace all the vacuum lines everywhere.
also see this:

[iMore]

Originally Posted by BashShah

you know, I had a similar issue, and you can not tell with these braided lines what is melted under it....or deteriorated.
but it seems to be the line that goes to the turbo itself.
why not just replace all the vacuum lines everywhere.

Yup! Definitely an option. It won’t be a bad thing and probably needs to be done anyway, at this point. But, just tired and frustrated at this point not being able to pinpoint such a rather minuscule issue/leak! What I’m afraid of is exactly what’s happened at this point… replace those lines and STILL not remediate the issue. Lol

[BashShah]

Originally Posted by iMore

Yup! Definitely an option. It won’t be a bad thing and probably needs to be done anyway, at this point. But, just tired and frustrated at this point not being able to pinpoint such a rather minuscule issue/leak! What I’m afraid of is exactly what’s happened at this point… replace those lines and STILL not remediate the issue. Lol

replacing lines is not going to cost you over $15.
so start there and rule it out.
then lets see if a smoke test is called for or not.

[iMore]

Ok… I’m realllly at a loss now! Any help/knowledge you all can provide would be greatly appreciated.

Hidden Boost Leak I can’t seem to find. At all. it’s been months and I feel like I’ve addressed ALL the possible failure points... but it’s STILL happening! Car goes into “half engine” mode at about 70mph+ or WOT. Otherwise, car drives absolutely fine, no issues whatsoever.

In my attempts to resolve, here’s what I’ve done so far:
New Charge Pipe
New VC
New FMIC
Replaced all vacuum hoses (for good measure)
Replaced DV
Inspected/cleaned all connection points/fittings. No issues.

I’ve ran enough smoke through this thing to give it cancer. It’s definitely a leak, the problem is that it’s not clearly visible as to where exactly coming from. It’s in the general area of the wastegate and DV. Eliminated the wastegate as I can see somewhat clearly, and there’s no smoke coming from it. Process of elimination leaves the DV. So, I just took on the task of replacing the DV with a TS Plumback. (0/10 - do not recommend! it’s an absolute PIA!)
Got that in finally. While doing that, I also added a 5.5” FMIC with all the pipes, just for good measure. Got it all back on, car turned on, and BAM!

Same issue, same codes, and same smoke from the same area.

I DONT GET IT!!

See photo for illustration - just a reference photo… but smoke/leak appears to be coming from the area circled. It seems to be spewing out horizontally directly toward the front of the car. How!?
What can it possibly be at this point? The turbo itself?? Maybe a small crack in the manifold? Or, a bad wastegate!? (No other wastegate issues or rattle though)

I’ve even tried the soapy water trick, I can’t get any visible bubbles, looking from both up top and from below the car.

I’m completely lost at this point!